This invention relates to apparatus for lifting crops ahead of a farm crop harvesting machine, and more particularly to an improved means for attaching such apparatus to said machine.
The apparatus of the invention includes a mounting bracket for attaching to the farm machine, and a pick-up bar to which is attached a grain lifting tool, or the like. A linkage means, having an upper end pivotally connected to said mounting bracket and a lower end pivotally connected to said pick-up bar, allows said pick-up bar to swing rearward relative to said mounting bracket. A preferred embodiment of said linkage means includes a solid link pivoted at each end. An alternate embodiment provides that the linkage means be adjustable in length.
The rear portion of the pick-up bar is slidably disposed through a guide opening in a guide frame, said guide frame being rigidly attached to the mounting bracket. Limiting means are provided on the pick-up bar which limit a forwardmost position of said pick-up bar relative to said mounting bracket. The limiting means can be made adjustable so that the pick-up bar remains substantially horizontal when in said forwardmost position for all lengths of said linkage means.
The crop lifting apparatus of the present invention is attached to a forward end of the farm machine. Traveling in close proximity to a ground surface, the apparatus slides under the stalks of the crop forcing the stalks up and back into the cutting teeth on the machine. Such tools are more particularly used when said crops have been flattened against the ground by rain, hail, wind or the like; in such instances, the crops must be raised up to the cutting teeth of the machine for harvesting.
A problem arises with crop lifting apparatus when they encounter obstacles along the surface of the ground. A rigidly attached apparatus will twist to one side and may twist downward or upward as well, resulting in damage to the apparatus which frequently requires immediate repair or replacement. Prior crop lifting apparatus have tried to solve this problem by providing a single pivoting means such that the front of the tool will swing upward from the obstruction, as disclosed in U.S. Pat. Nos. 2,734,332 to Fisher, 2,960,814 to Babcock, 4,022,000 to Coxbill and 3,821,877 to Weinheimer. However, such pivoting means may not prevent the tool from being twisted to one side or downward.
The present invention offers an improvement over the prior art in that the pick-up bar will swing rearward when the forward end of said pick-up bar encounters an obstacle on the ground, and the guide frame, pick-up bar and linkage means are so arranged and constructed that as said pick-up bar swings rearward from said forwardmost position, the front end of said pick-up bar is lifted, thus raising said front end above the obstruction. This rearward and upward motion of the front end of the pick-up bar eliminates the tendency to twist up, down or to one side as with previous crop lifting tools.
U.S. Pat. No. 3,821,877 to Weinheimer discloses, at FIGS. 10-13, a crop lifting apparatus in which the forward end of the tool is raised as a rear end portion slides rearward against a rearwardly and downwardly sloping fixed wedge surface. A mechanical spring is required to return the tool to its forwardmost position. To move the tool, a force must be applied which is sufficient to overcome the frictional forces from the various sliding surfaces, the initial spring loading and the increasing spring loading as the tool is moved and the spring deflected.
With the apparatus of the present invention, on the other hand, a gravity return means, rather than mechanical means such as a spring, returns the pick-up bar of the present invention to its original forwardmost position after the tool has passed over the obstacle. Said gravity return means is provided by said mounting bracket, pick-up bar and linkage means being so arranged and constructed that when said pick-up bar is in its forwardmost position relative to said mounting bracket, said linkage means is no further forward than a vertical position thereof, so that gravitational forces acting on said pick-up bar always urge said pick-up bar towards said forwardmost position, said forwardmost position being a normal operating position of said pick-up bar.
In the apparatus of the present invention, a runner means is defined by a smooth lower surface of the pick-up bar for traveling in close proximity to the ground. A lower portion of the guide bracket is the only part of the apparatus which extends below said runner means, and said lower portion of said guide bracket extends rearward to minimize interference with the ground. All other moving parts are above said runner means. Thus, the present invention is further distinguished from the prior art, and particularly from Weinheimer which has various items including the return spring protruding below the tool. Weinheimer requires the use of a shoe means to raise said protrusions and spring to prevent them from being dragged along the ground, but said protrusions and spring still are likely to become obstructed by dirt, grain stalks or the like, thereby adversely affecting the performance of the tool.
From the foregoing description of the present invention, it will be apparent that an important object of the invention is to provide an improved crop lifting apparatus in which a pick-up bar of said apparatus will swing rearward on a linkage means when said apparatus encounters an obstruction on the ground.
A further object of the invention is to provide an improved crop lifting apparatus in which the front end of the pick-up bar of said apparatus is raised as said pick-up bar swings rearward.
A further object of the invention is to provide a limiting means to define a forwardmost position of said pick-up bar.
A further object of the invention is to provide an improved arrangement and construction of said apparatus whereby a gravity return means will return said pick-up bar to said forwardmost position.
A further object of the invention is to provide an improved runner means for traveling in close proximity to a ground sur- face.
Additional objects and advantages of the invention will become apparent from the following detailed description of a preferred embodiment of the invention when the same is read in conjunction with the accompanying drawings which illustrate such embodiment.